The present invention generally relates to a communication system that generally utilizes a series of base stations or repeaters to receive incoming signals which eventually are processed through a central electronics bank and then dispersed to several consoles that are to acknowledge such incoming signals.
Typically, in a communications system utilizing consoles that communicate with signals generated in the field, a base interface module (BIM) is assigned to a particular base station or repeater that interfaces with a communications channel that carries signals to and from subscribers out in the field. An operator multiplex interface (OMI) is normally assigned to a single console in the system and is also assigned to a particular BIM in order to allow the console to communicate with someone in the field through that particular BIM and repeater. The plurality of BIMs and OMIs are typically located within a central electronics bank (CEB) and communicate with each other through the use of a CEB data bus. Communication channels requiring acknowledgments are designated as RF signalling channels and use an RF signalling BIM as an interface.
Where a particular communication system has an automatic acknowledgment feature of some kind this feature normally requires that every message sent from a field unit or subscriber must be acknowledged by the fixed end equipment, such as one of the consoles. This procedure is simple when one fixed end unit exists since it acknowledges all received messages. However, problems start to occur when a system is used that utilizes a central electronics bank having several control consoles available for acknowledging incoming messages. Unless some cooperation exists between the consoles, all consoles will send acknowledgments at once. This method of operation tends to generate very uneven loading on the CEB data bus, consequently, overloading the modules on the data bus. The throughput capacity of the CEB data bus is much higher than the processing capabilities of the boards on the bus. If a large number of data packets is put onto the bus, microprocessors can become overburdened. With very large data bursts, the microprocessor loading is such that users notice a slow down in the console's response. Therefore, care must be taken in designing data protocols to prevent bursts of data.
Another problem that exists with the current method of acknowledging signals from the field is that overloading of one particular control console may occur. Currently in the CEB, there are instances in which a single control console performs an operation that may be shared with another console. The single console may be required to perform additional duties such as general fault maintenance for determining when to activate standby boards in the CEB. The existing approach assigns a single console to perform duties for all consoles. This approach works for a limited number of duties, but would overburden the one control console if applied in addition to acknowledgment responsibilities. The single console response time could degrade in a very busy system requiring a large number of acknowledgments for more than one communications channel.
Another problem that can exist with an acknowledgment system is that there may be a failure to acknowledge messages due to assignment changes in the system. Typically a control console is only allowed to acknowledge messages on channels that it is controlling or to which it is assigned. For a static system, the acknowledgment duties to be performed by each console can be determined at system set-up. The duties can be level loaded among the consoles and all channels can be assigned to a console that will handle acknowledgments for those channels. If, however, a console fails, its acknowledging duties will not be performed, hence the system stops functioning.
Therefore, a need exists for a method of reassigning the acknowledgment duties, within a communication system, to subscribers where failures or overloading occurs within the communication system.